approval vs permission

approval

noun
  • An expression granting permission; an indication of agreement with a proposal; an acknowledgement that a person, thing, or event meets requirements. 

  • Something mailed by a seller to a collector to match their stated interests; the collector can approve of or return the item. 

  • An expression of favorable acceptance and encouragement; a compliment that also condones. 

permission

noun
  • The act of permitting. 

  • authorisation; consent (especially formal consent from someone in authority) 

  • Flags or access control lists pertaining to a file that dictate who can access it, and how. 

verb
  • To grant or obtain authorization for. 

How often have the words approval and permission occurred in a corpus of books? (source: Google Ngram Viewer )